Method and apparatus for overlaying two CDMA systems on the same frequency bandwidth

• US 6,882,631 B1
• Filed: 09/13/1999
• Issued: 04/19/2005
• Est. Priority Date: 09/13/1999
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Tiedemann, Edward G. Jr.
• Primary Examiner(s): Duong, Frank
• Assistant Examiner(s): Jagannathan, Melanie
• Application Number:
  US09/395,300
• Time in Patent Office: 2,045 Days
• Field of Search: 370/329, 370/342, 370/350, 370441-443, 370/500, 370/503, 370/516, 370330-335, 370/348, 455/436, 455/437, 455/442, 455/450, 455524-525, 455/453, 455/447, 455/515, 455/506, 375/358, 375/130
• US Class Current: 370/335
• CPC Class Codes: H04B 7/2668 Arrangements for Wireless Code-Division Multiple Access [CDMA] System Synchronisation, for code acquisition H04B1/7075, for code tracking H04B1/7085
• CPC Class Codes: H04B 7/2696 Over the air autonomous synchronisation, e.g. by monitoring network activity H04B7/2693 takes precedence
• CPC Class Codes: H04J 13/004 Orthogonal

Abstract

In order to align the timing of an overlay base station to the timing of an existing base station, a sync unit is introduced into the system. The sync unit has a first receiver configured to receive a first signal, the first signal having a first CDMA channelization. The first receiver is configured to produce an indication of a timing of the first signal. The sync unit also has a second receiver configured to receive a second signal, the second signal having a second CDMA channelization. The second receiver is configured to produce an indication of a timing of the second signal. The sync unit also has a time error detection unit configured to compare the timing of the first signal and the timing of the second signal to determine a relative timing offset thereof.

Claims

1. A method of overlaying a second CDMA system over a first CDMA system comprising the steps of:

receiving a first signal and one or more first information signals, said first information signals using a first CDMA channelization and providing service to a first coverage area;

receiving one or more second information signals, said second information signals using a second CDMA channelization and providing service to at least a portion of said first coverage area;

determining a power level of said first signal;

determining a power level of each of said one or more first information signals;

determining a power level of each of said one or more second information signals; and

determining a level of loading within said at least said portion of said first coverage area based upon said power level of said first signal and said power levels of said one or more first and second information signals.

2. The method of claim 1, further comprising the step of transmitting said one or more first information signal and said one or more second information over a first antenna.

3. The method of claim 1, wherein steps of receiving comprise the step of receiving signal energy over a second antenna.

4. The method of claim 1 wherein steps of receiving comprise the step of using a coupler.

5. The method of claim 1 further comprising using said level of loading to determine an admission criteria for admission of information signals transmitted using said second CDMA channelization.

6. The method of claim 1 wherein said second CDMA channelization has a wider spectrum than said first CDMA channelization.

7. The method of claim 1, wherein said first CDMA channelization has a wider spectrum than said second CDMA channelization.

8. The method of claim 1 wherein said first signal is a pilot signal.

9. A CDMA system comprising:

a first base station configured to transmit a first signal and one or more first information signals, said first information signals providing service to a first coverage area;

a second base station configured to transmit one or more second information signals having a second CDMA channelization, said second information signals providing service to at least a portion of said first coverage area; and

a sync unit configured to obtain a power level corresponding to each of said first signal and said one or more first and second information signals;

wherein said second sync unit is further configured determine a level of loading within said at least said portion of said first coverage area based upon said power measurement of said first signal and said power measurements of said one or more first and second information signals.

10. The CDMA system of claim 9, wherein said second base station is further configured to determine an admission criteria for admission of information signals transmitted using said second CDMA channelization.

11. A sync unit comprising:

a first receiver configured to receive a first signal having a first CDMA channelization and to produce an indication of a timing of said first signal;

a second receiver configured to receive a second signal having a second CDMA channelization and to produce an indication of a timing of said second signal; and

a time error detection unit configured to compare said timing of said first signal and said timing of said second signal to determine a relative timing offset indication to be used to adjust a transmission timing of said second signal.

12. The sync unit of claim 11 wherein said sync unit further comprises an antenna through which said first and second signal are received.

13. The sync unit of claim 11 wherein said sync unit further comprises a coupler through which said first and second signal are received.

14. The sync unit of claim 11, wherein said first and second receivers share at least a portion of hardware.

15. The sync unit of claim 11 wherein said first and second receivers are a single time-shared unit.

16. The sync unit of claim 11, further comprising a phase error detection unit configured to compare a phase of said first signal and a phase of said second signal to determine a relative phase offset indication to be used to adjust a transmission phase of said second signal.

17. The sync unit of claim 11 further comprising a power measurement unit configured to determine a power level of said first and second signal and a compare unit configured to determine a level of loading within a coverage area corresponding to said first and second signals.

18. A sync unit comprising:

a first receiver configured to receive a first signal and one or more first information signals having a first CDMA channelization, said first information signals providing service to a first coverage area;

a second receiver configured to receive one or more second information signals having a second CDMA channelization, said second information signals providing service to at least a portion of said first coverage area;

a power measurement unit configured to determine a power level of said first signal, a power level of each of said one or more first information signals, and a power level of each of said one or more second information signals; and

a compare unit configured to determine a level of loading within said at least said portion of said first coverage area based upon said power level of said first signal and said power level of said one or more first and second information signals.